The Duke and Duchess of York said their younger daughter and Mr Brooksbank became engaged while in Nicaragua earlier this month.
Princess Eugenie and Brooksbank have yet to set a date for their wedding, but they will hold the ceremony at St. George's Chapel, which is the same church Markle and Prince Harry will be tying the knot in on May 19.
Sarah has returned to Balmoral in recent years, staying for short breaks with ex-husband Prince Andrew, Queen Elizabeth II and Princesses Beatrice and Eugenie.
Yet, Eugenie and Jack fawned over each other as they spoke of falling in love at first sight and how the relationship felt different since Buckingham Palace announced the news. While talking to host Matt Baker, the bride-to-be revealed how the Queen was one of the very first people to hear about the happy news, and that she was "very happy" for them.
Brooksbank added, "She was incredibly happy and wished us well, which was very fantastic, that she was so happy for us".
Fans of the royal family are in for a treat this year - not one royal wedding, but two!
Prince Harry and Meghan Markle aren't going to be the only royal couple this year.
The Queen's granddaughter shared his proposal was a "complete surprise", even though they have been dating for the past seven years.
Princess Eugenie is to marry her long-term boyfriend Jack Brooksbank, Buckingham Palace has announced.
Prince Andrew said: "I'm absolutely overjoyed".
Mr Brooksbank's parents, Nicola and George, also spoke of their happiness.
Her fiancé, Jack, explained that it's a very rare pink-orange padparadscha sapphire, usually found in Sri Lanka and named after the colour of a lotus blossom.
Sarah "Fergie" Ferguson wrote: 'We love jack and I AM SO EXCITED to have a son, a brother and a best friend.
The princess works in the arts as a director at gallery Hauser and Wirth.
Taking to Twitter, the Duchess posted a picture of the newly-engaged couple featuring the words: "A total embrace of goodness and joy".
Women's Marches Draw Crowds in Cities across the US
In Morristown, New Jersey , that state's new first lady told a crowd she was a victim of sexual violence while attending college. REUTERS/Steve MarcusCher waves at the conclusion of her remarks during the Women's March rally in Las Vegas, Nevada, U.S.